On the other hand, activating mutations of the PIK3CA gene shift tumor behavior, enhancing cell proliferation and migration and tumor invasiveness and metastasis [84], being reported in breast cancers [83], colorectal cancers, head and neck squamous cell carcinoma, and appendiceal cancer, including low-grade appendiceal mucinous neoplasms [12,30], appendiceal adenocarcinomas [85], and mucinous adenocarcinomas of the appendix [33]. This evidence concerns the gene PIK3CA and breast cancer.